Hydraulically dampered cross equalized trucks



April 22,v 1969 ca. w. coPE 3,439,630

HYDRAULICALLY DAMPERED CROSS EQUALIZED TRUCKS I Sheet Filed March 2, 19.65

Inventor; Geoffrey W. Cop e FIG. l

his Attorney April 22, 1969 G. w. coP

-HYDRAUL'ICALLY DAMPERED CROSS EQUALIZED TRUCKS Filed March 2, 1965' Sheety 2 `of 5 .4 lnvenior:v GeofffeyW. Cope By id his Aorney Aprill 22, 1969 G. w. COPE HYDRAULIGALLY DAMPERED oaoss EQUALIZED Tnuxs Sheet y Filed March 2, 1965 ne. e

l FIG. e

FIG. 9

Inventor: GeoffreyW. Cope` United States Patent O 3,439,630 HYDRAULICALLY DAMPERED CROSS EQUALIZED TRUCKS Geoffrey W. Cope, Williamsville, N.Y., assignor to Symington Wayne Corporation, Salisbury, Md., a

corporation of Maryland Filed Mar. 2, 1965, Ser. No. 436,610 Int. Cl. B61f 5/10, 3/10, 5/12 U.S. Cl. S-196 16 Claims ABSTRACT OF THE DISCLOSURE This invention relates generally to railway trucks and particularly to freight car trucks.

To reap benefit from their position as the low cost freight carrier in terms of motive power requirements per ton mile, the railroads for many years have progressively increased the lengths of their freight trains as more powerful locomotives became available and it is now commonplace to use snubbed trucks on freight cars for enabling them to be moved at passenger car speeds. As an aid in regaining ground lost in recent years to competitors and obtaining a more proportionate share of the freight business, the most recent trend among railroads in transporting freight has been toward increasing the capacities of individual freight cars both in specialized cars and in cars of otherwise conventional types. Concurrently, there has been increasing interest in both automation and maintenance-free operation.

Conventionally, freight car trucks are four-wheeled, with the imposed load suspended on coil springs and the periodicity of oscillation to which such springs are subject damped or snubbed by mechanical friction devices to adapt them for high-speed service. Although wear is an ever-present factor, due to the' use of mechanical friction for snubbing, four wheel trucks are in use in pairs under cars of up to 125 tons capacity. However, in highspeed freight service, such trucks pose a number of problems. The dependence on friction snubbing produces rapid wear in the friction surfaces, the lack of lateral freedom for the wheel and axle assemblies in the more usual truck in which the supporting springs are interposed between a bolster and the side frames, causes nosing and wear of truck parts and wheel flanges, and there is also excessive Wear in the center plate due to uncontrolled swivelling as well as to nosing. Also, the usual four wheel truck does not have adequate ride qualities at the higher speeds and is incapable of coping with synchronous roll conditions in high center of gravity of cars.

But probably the main shortcoming of four wheel truck under freight cars of the higher capacities now contemplated, is the limitation on the maximum load imposed by the bearing area between the four whe'els and the rails. Since the bearing area increases with increase in the size of the wheels, there is advantage to capacity in using larger diameter Wheels, up to the practical maximum of 38 inches, but only at the expense of increasing the overall height of the car. And even with increased wheel size, the concentration of the load is such that the best of present trackage can be expected to fail excessively when subjected to heavy trafc involving cars of over 100 tons 3,439,630 Patented Apr. 22 1969 rice carried on four wheel trucks. The obvious expedient would be to use six wheel trucks on cars above that capacity, so as to distribute the load among six wheels rather than four,and this would also be of advantage on cars down to around tons; but there are obstacles. The present designs of six wheel freight car trucks are few and complex andvery costly compared with four wheel trucks. All are disproportionately heavy, with consequent reduction in the revenue load, and difficult to service, especially when the center wheel and axle assembly is involved. Too, both the wheel base length and the center plate height in most cases are above desirable limits.

The primary object of the' present invention is to provide an improved railway truck which can have either two or more axle or wheel and axle assemblies and, in the former case, eliminates the problems posed by present four wheel trucks in high speed freight service and, in the latter, removes the present obstacles to the use of six wheel trucks on bigger freight cars.

Another object of the invention is to provide a railway truck which, by resiliently supporting its side frames on separate journal boxes and hydraulically equalizing the forces applied through the wheels, can have its -bolster rigid with its side frames, thereby simplifying and reducing the cost of production and maintenance in all its versions over conventional trucks.

An additional object of the invention is to provide a railway truck which not only equalizes applied forces and prevents synchronous lateral roll of a car body, but aso hydraulically snubs the supporting springs, with consequent elimination of the wear attendant the use of the usual mechanical friction-snubbing devices.

A further object of the invention is to provide a railway truck which, in its six wheel version, is far more compact and less expensive than present six wheel trucks and enables both the wheel base length and the center plate height to be kept well within desirable limits.

A further object of the invention is to provide a railway truck having a bolster rigid with the side frames and resiliently supporting the side frames on separate journal boxes, wherein interconnected hydraulic cylinder units serve not only as snubbers but also as resilient load supports.

Other objects and advantages of the invention will appear hereinafter in the detailed description, be particularly pointed out in the appended claims and be illustrated in the accompanying drawings, in which:

FIGURE l is a plan view of a preferred embodiment of a six wheel version of the improved railway truck of the present invention;

FIGURE 2 is a side elevational view of the truck of FIGURE l;

FIGURE 3 is a vertical sectional view taken along lines 3 3 of FIGURE l;

FIGURE 4 is a fragmentary vertical sectional View taken along lines 4-4 of FIGURE l;

FIGURE 5 is a fragmentary vertical sectional view taken along lines 5-5 of FIGURE l;

FIGURE 6 is a fragmentary vertical sectional view on an enlarged scale taken along lines 6 6 of FIGURE 3;

FIGURE 7 is a fragmentary horizontal sectional view taken along lines 7 7 of FIGURE 6;

FIGURE 8 is a fragmentary horizontal sectional view taken along lines 8-8 of FIGURE 6; and

FIGURE 9 is a schematic view of a check valve such as used in the hydraulic system of the truck.

Referring now in detail to the drawings in which like reference characters designate like parts, the improved railway truck of the present invention, while utilizable on other types of cars, is designed particularly for freight cars for use in high speed freight service. The truck is basically the same in all of its versions, but most pronounced in its differences and advantages over the prior art in its three or multiple axle or wheel and axle assembly version and, accordingly, a six wheel truck has been illustrated as exemplary of the invention,

In both two or plural and three or multiple axle versions, the improved truck is comprised basically of a generally H-shaped frame 1 formed of a pair of side frames 2 and a bolster 3 extended laterally between and connecting the side frames. As opposed to a conventional railway truck in which the bolster is at least separate from and, usually, is also resiliently supported on the side frames, the bolster 3 and side frames 2 of the frame 1 of the truck of this invention are fixed to or rigid with each other. Conveniently cast either as a single casting or as separate units and then welded together, depending on the mold capacity of the particular plant, the side frames 2 and bolster 3, as cast or after connection or joining, together provide in the frame 1 an integral or unitary rigid structure.

The side frames 2 are of the unitary pedestal type for receiving or accommodating separate journal boxes 4, upon which they are resiliently supported by suitable resilient supports or supporting springs 5. Each of the journal boxes 4 receives and suitably journals one of the journals 6 at the ends of the axles 7 and, in turn, is received or accommodated, for at least vertical movement relative to the side frame 2 supported upon it, in a downwardly and laterally opening recess or opening 8.

Bounded at the sides by confronting, upright or vertical jaws, guide columns or pedestal guides 9 spaced longitudinally of the side frame 2 in which it is formed, each journal box recess 8 is bounded at the top by a web or upper wall 10 and, by its guide columns, slidably receives and guides the journal box in its relative vertical movement. While the journal box recesses 8 in each side frame 2 are spaced longitudinally thereof, the particular arrangement will depend upon the number of axles the truck has. In any case, there ordinarily will be a recess adjacent each end of the side `frame and if, as will usually be the case, the truck has at most 3 axles, the recess for the third or middle axle is best centered, longitudinally'of the side frame midway, between the end recesses.

The rigidness of the bolster 3 with the side frames 2, while in part stemming from the resilient support or mounting of the side frames on the separate journal boxes 4, in the main is derived from a hydraulic system 11 with which the truck is litted. The hydraulic system 11 includes a hydraulic cylinder unit 12 for each journal box 4 and an open hydraulic connection or open piping i 13 between the several units, conveniently in the form of a rigid ring pipe 14 mounted on the underside of the bolster 3 around the center plate or bearing 15, and armored flexible lead pipes or tubes 16 tapped into the ring pipe 14 at spaced points and each leading to one of the units. The system also includes one or more accumulators or supply tanks 17 connected to the ring pipe 14 for maintaining a full supply of oil or other liquid under pressure in the units 12 and connecting piping 13 and under certain conditions receiving excess liquid therefrom.

Mounted and acting vertically `between one of the journal boxes 4 and the side frame 2 mounting the box, each hydraulic cylinder unit 12, to perform its intended functions, includes a cylinder 18 and a piston 19 slidably or telescopingly received in and projecting from the cylinder. Each hydraulic unit 12 need only be single acting and can have its cylinder 18 connected to one and its piston 19 connected to the other of the related side frame 2 and journal box 4. However, since the lead pipes 16 lead to the cylinders 18, it usually will be desirable to v mount the cylinders stationarily in the side frames 2 and have the pistons 19 engage the journal boxes 4. By seating each cylinder against lateral movement in a pocket 20 formed in the side frame 2 above and centered laterally or transversely on the related or adjoining recess 8 and releasably securing it in the pocket with its closed upper end 21 bearing against and backed by the top wall 22 of the side frame, as by the illustrated bolt 23, a positive connection between the piston 19 and the journal box 4 can be dispensed with. Instead, the piston can simply have its outer end 24 in bearing engagement or contact with the top wall 25 of the journal box, preferably through a wearresistant, lubricious or low frictional coeliicient bearing plate or spacer 26 made of reinforced nylon, Teiion or other suitable material.

With each cylinder 18 so mounted and having in its upper end above the piston 19, an oil or other suitable hydraulic liquid chamber 27 in open communication with the chambers of the other cylinders through the connecting piping 13, and individually bleedable as necessary to remove any entrapped air through a normally plugged bleed port 28, each hydraulic cylinder unit 12, on upward movement of the related or connected journal box 4 relative to the side frame 2, will be contracted or compressed and the volume of its oil chamber correspondingly reduced, by telescoping of the piston 19 into the cylinder 18. Conversely, downward movement of the journal box 4 in its recess 8, relative to the side frame 2 will be accompanied by an expansion or extension of the hydraulic unit 12 as the piston 19 is projected from the cylinder 18 and held or maintained in contact with the journal box 4 by the pressure in the hydraulic system 11.

While the oil or other suitable hydraulic liquid with which the hydraulic units 12 and connecting piping 13 are filled is incompressible, the pressure in the system suitably is derived from compressed air or other gas injected into each accumulator 17 and maintained therein at a predetermined pressure of the order needed for the particular installation. lf, as is convenient, each accumulator 17 is of the type shown in my copending application entitled Hydraulically Dampened Cross Equalized Truck, Ser. No. 434,981, filed on Feb. 24, 1965, and there is in the lead line 29, between each accumulator and the ring pipe, a regulator or adjustable check valve 30 of the type also shown in that application and illustrated schematically in FIGURE 9, the compressed air will be contained in the air side of the accumulator 17 and act against the liquid on its liquid side through a floating piston (not shown). Through the regulator valve 30, which permits a free flow of liquid from the accumulator 17 to the connecting piping 13 and a restricted or choked, controlled or regulated flow in the opposite direction, the air pressure in the accumulator 17 not only will maintain the hydraulic system lled but, through the liquid, also will maintain the predetermined pressure throughout the system. Thus, despite the incompressibility of the liquid in the hydraulic system 11, the hydraulic cylinder units 12 by being compressible against the pressure of a compressible medium (the air or other gas in each accumulator 17) are resilient and can resiliently support a load, with their load capacity determined by the applied pressure and their number and internal cross-sectional area.

On the above basis, the cylinder units 12 alone might be used as the resilient supports for the side frames 2 upon the journal boxes 4. However, a system dependent for cushioning entirely upon the transmission of applied forces to the compressed air through the hydraulic liquid and pressurized at a predetermined pressure suitable for the particular application, usually will be too stiff to cushion the high frequency, low amplitude shocks Or forces to which a truck under `a car in a moving train is continuously subjected. By the same token, such shocks could be capable under certain conditions of overstressing the hydraulic system 11 and particularly the piping 13. Consequently, it is desirable in any case to protect the hydraulic system 11 from such shocks and this is readily accomplishable by inserting in the lower end of each of the pistons 19 a resilient pad or block 31 made of a material that is both sufficiently resilient to absorb such shocks and inert to the liquid in the system, such as neoprene or Buna-N rubber, the compressibility of which has been increased by introducing nitrogen bubbles in the molding operation. With this arrangement, any compression of a cylinder unit 12 under an applied force must first compress the resilient pad 31 before it can transmit the remainder or unabsorbed part of that force to the rest of the hydraulic system 11.

Even though, with the resilient pads 31 or comparable means, for absorbing the high frequency, loW amplitude shocks, the hydraulic system 11 might be used to support the full load upon the journal boxes 4, it is preferred to support only part of the load, in the range of 4around 2O to 50%, by the hydraulic system and depend for the remainder of the resilient support upon mechanical springs, such as the coil springs 32 of the illustrated truck. To accommodate the addition-al springing, each journal box has on its lower part below the recess 8, a pair of upwardly facing shelves, ledges or wings 33 outstanding, longitudinally of the side frame 2, from its opposite sides and confronting downwardly facing spring seats 34 formed on the side frame at corresponding sides of the recess. Seated in vertical disposition between the shelves 33 on each journal box 4 and the confronting spring seats 34 on the side frame 2 and, for balance, paired on opposite sides of the journal box, the coil or other suitable mechanical springs 32 will react or respond to any vertical forces applied to the journal boxes and, by acting between the journal boxes and the side frames, give resilient support to the frame 1 and the car body (not shown) mounted thereon, whenever such forces occur.

By combining the mechanical springs 32 with the protected hydraulic system 11, the truck, in either its two or its three or multiple axle version, has adequate springing for any of the shocks to which it may be subjected in service. Too, any compression of the mechanical springs must be accompanied by a like compression of one or more of the hydraulic units 12 and the latter compression, in cushioning high frequency, low Iamplitude forces by the pads 31 and generating heat by fluid friction in the piping 13 and the choked flow from the piping into either accumulator 147 through the intervening regulator valve 30, in response to forces or shocks of higher amplitude, will partly absorb any vertical forces applied through any journal box. Thus, the hydraulic system 11 will effectively snub or damp any vertical oscillations of the mechanical springs and there is no need to resort for snubbing to the usual wear-producing mechanical friction snubbing devices.

The improved truck in any of its versions readily can accommodate the limited lateral motion of the axles 7 relative to the frame 1, required under certain service conditions. In moving vertically relative to a side frame 2, each journal box 4 rides between the guide columns 9 of its recess 8 and presents, for sliding or bearing engagement with inner or confronting, vertically disposed, fiat or planar and parallel bearing surfaces 35 of the guide columns, correspondingly disposed flat bearing faces or surfaces 36 on its opposite sides intermediate its ends. The bearing faces 3-6 on the journal box 4 are bounded laterally by inboard and outboard gibs 37, the lateral spacing between which is sufficiently greater than the width of the bearing surfaces on the guide columns 9 to accommodate the desired lateral movement of the adjoining axle relative to` the side frame. Although not shown, it is, of course, possible, if desired, to form the column surfaces 35 on wear plates attached to the columns, rather than directly on the columns. Notched at the sides to receive and be positioned or located by the guide columns 9 and moving vertically with the journal boxes 4, the lubricious or low frictional coefficient, wearresistant bearing plates or spacers 26, `depending on the width of the notches 38, will either move laterally with the journal boxes 4 or be held against such movement and in any case will minimize the effect of the journal box 4 upon the piston 19 and vice Versa on relative lateral movement thereof.

The refinements upon the basic truck which are embodied in the illustrated six wheel truck, are also desirable in the four wheel version. Thus, the piston 19 of each hydraulic unit 12 should be covered by -a boot 39 to protect the sliding joint Ibetween itself and the related cylinder 18 from dirt or other foreign matter. Conversely, escape of liquid from the hydraulic system 11 through any such sliding joint is prevented by suitable gasketing and, for each illustrated piston 19 which has its lower end formed as a cup 40 for seating the pad 31 and a hollow plug 41 threaded into the open -upper end of the cup, may take the form of a piston cup seal or gasket 42 on the upper end of the plug and an O-ring 43 between the plug `and the cup.

In keeping with present trends in freight cars for high speed service, the illustrated truck has the journals 6 on the ends of the axis 7 journaled in cartridge bearings 44. To mount the journal boxes 4 on the cartridge bearings 44, each journal box is apertured to receive the adjoining bearing, with the aperture 45 cyclindrically concave at the top to conform to the upper half of the cartridge bearing and enlarged therebelow so as to permit the bearing to be inserted and removed as required. In service, each cartridge bearing 44 is held by the caps 46 at its ends against any or at most limited axial movement in its cylindrically concave seat 47 in the upper part of the aperture 45.

In any of its versions, the improved truck prevents the objectionable nosing, experienced in a conventional truck on unsquaring of its side frames relative to its separate bolster, by the rigidity of the bolster 3 with the side frames 2 and this same rigidity prevents the rotation of the lbolster relative to the side frames, which in a conventional truck takes place on stopping and starting. Also, with the convenient and safe mounting of the one or more accumulators 17 on one or each side of the Ibolster 3 and the ring pipe 14 on the bolsters underside, the improved truck is readily adapted for mounting of the hydraulic units 12 and the lead lines 16 to take them, out of harms way, inside the frame 1. As mentioned earlier, the improved truck, while basically different from prior trucks, is most pronounced in its differences in the illustrated six wheel version. As opposed to prior six wheel trucks, not only are the side frames 2 and bolster 3 unitary with consequent ease in holding both the wheel base of the truck and the height of its center plate 15 within any reasonable limits, but the elimination of the usual jointing between parts of each of the side frames makes the wheel and axle assembly at the center as accessible for maintenance as either of the end assemblies.

As in any fluid spring system, the load that can be supported by the hydraulic system 11 depends -upon the pressure in the system and the number and effective crosssectional area of the hydraulic units 12. However, over an air spring system, the hydraulic system 11 of the improved truck of this invention is peculiarly capable of snubbing vertical oscillations of the coil or other mechanical springs 32, due to the relatively high energy or force absorption of liquid friction on movement of liquid in the system in response to a force applied at any of the journal boxes 4.

The application of the springing between the side frames 2 and the journal boxes 4, rather than between the side frames and the bolster 3, is a prerequisite to the rigidity of the bolster with the side frames. But the freedom of the improved truck from unequal forces, which in a conventional truck necessitate relative movement between the bolster and the side frame, regardless of the location of the supporting springs, is the direct result of the hydraulic system 11. Since the hydraulic cylinder units 12 and the connecting piping 13 are at all times maintained filled with liquid by the pressure in the one or more accumulators 17, the system 11 is governed by Paseals Law and, except for the high frequency, low amplitude forces absorbed by the resilient pads 3.1, any vertical force or vertical component of a force applied to any of the hydraulic units is distributed or divided equally between or among all of the units. Thus, the hydraulic system 11, with its hydraulically interconnected hydraulic cylinder units 12, provides longitudinal, diagonal and cross-equalization of applied vertical forces.

As in the truck of my earlier mentioned co-pending application, the equal distribution or equalization, among the hydraulic cylinder units 12, of a vertical force applied through any of the journal boxes 4, has the further salutary effect of preventing synchronous car body roll in high center of gravity cars due to vertical rail deviations.

In such case, a lifting force is applied to the truck at the side of the deviation with consequent compression of the adjoining hydraulic cylinder unit or units 12. Immediately, the applied force is transmitted to the other units, with accompanying ow of the liquid displaced from the initiating unit or units to those units not acted directly upon by the force. Consequently, any lifting force due to a vertical rail deviation at one side, by generating its own counter in the form of a lifting force of substantially the same order 4at the other side, prevents any resultant lateral car body roll from progressing beyond the incipient stage. Like that of my copending application, the hydraulic system 11 of the improved truck of this invention, while snubbing any lateral car body roll from forces applied through the journal boxes 4, will not interfere with a slow car body roll, such as that experienced in rounding a curve as a result of the centrifugal force on the car body.

Where the hydraulic system 11 required to combat vertical forces applied only to one hydraulic cylinder unit 12 or to the units at one side of the truck, the regulator valve 30 interposed between each accumulator 17 and the ring pipe 14 could be simply a one-way check valve. However, when, as often happens, vertical forces are applied simultaneously or concurrently to both sides of the truck, the hydraulic system 1.1 Imust be relieved of the excess liquid displaced by the cylinder units at both sides. It is then that the choked or regulated ow in reverse, permitted by each regulator valve 30, comes into play to enable the excess liquid to tiow from the piping 13 into the adjoining accumulator 17, since, even though choked, the path to the accumulator is at that time the path of least resistance to iiow of the liquid.

From the above detailed description it will be apparent that there has been provided an improved railway truck which, with its hydraulic system, is particularly suited for use in high speed freight service and in one or another of its versions is adapted for use on freight cars of any size and load capacity. It should be understood that the described and disclosed embodiment is merely exemplary of the invention and that all modifications are intended to be included that do not depart from the spirit of the invention and the appended claims.

Having now described my invention, I claim:

1. A railway truck comprising journal boxes, side frames, means acting between each of the journal boxes and the adjoining side frame for resiliently supporting the side frames thereon, a bolster rigid with the side frames, and a hydraulic cylinder unit acting between each journal box and the adjoining side frame, said units being hydraulically interconnected for substantially instantaneously equalizing thereamong any vertical forces applied thereupon.

2. A railway truck comprising journal boxes, side frames, means acting between each of the journal boxes and the adjoining `side frame for resiliently supporting the side frames thereon, a bolster rigid with the side frames, a hydraulic cylinder unit acting vertically between each journal box and the adjoining side frame, open piping hydraulically interconnecting said units for substantially instantaneously equalizing thereamong vertical forces applied to any thereof, and means connected to said piping for maintaining said piping and units lled with liquid at a predetermined pressure.

3. A railway truck comprising journal boxes, side frames, means acting between each of the journal boxes and the adjoining side frame for resiliently supporting the side frames thereon, a bolster rigid with the side frames, a hydraulic cylinder unit acting vertically between each journal box and the adjoining side frame, open piping hydraulically interconnecting said units for substantially instantaneously equalizing thereamong vertical forces applied to any thereof, and gas pressure means connected to said piping for maintaining said piping and units filled with liquid at a predetermined pressure.

4. A railway truck comprising journal boxes, side frames, means acting between each of the journal boxes and the adjoining side frame for resiliently supporting the side frames thereon, a bolster rigid with the side frames, a hydraulic cylinder unit acting vertically between each journal box and the adjoining side frame, open piping hydraulically interconnecting said yunits for substantially instantaneously equalizing thereamong vertical forces applied to any thereof, means connected to said piping for maintaining said piping and units filled with liquid at a predetermined pressure, and valve means interposed between said piping and said maintaining means for permitting free ow of said liquid therebetween to the piping while restricting flow of said liquid in the opposite direction.

5. A railway truck comprising journal boxes, side frames, means acting between each of the journal boxes and the adjoining side frame for resiliently supporting the side frames thereon, a bolster rigid with the side frames, a hydraulic cylinder unit acting vertically between each journal box and the adjoining side frame, open piping hydraulically interconnecting said units for substantially instantaneonsly equalizing thereamong vertical forces applied to any thereof, means connected to said piping for maintaining said piping and units lled with liquid at a predetermined pressure, and regulator valve means interposed between said piping and said maintaining means for permitting free iiow of liquid therebetween to said piping while adjustably regulating the flow thereof in the opposite direction.

`6. A railway truck comprising a bolster, side frames laterally connected by and rigid with said bolster, a plurality of journal boxes mounted for at least relative vertical movement in each of said side frames, a hydraulic cylinder unit acting vertically between each journal box and the related side frame, open piping hydraulically interconnecting said units, and resilient means in each unit and reacting vertically against hydraulic liquid therein for absorbing high frequency, low amplitude forces applied thereof.

7. A railway truck comprising a bolster, side frames laterally connected by and rigid with said bolster, a plurality of journal boxes mounted for at least relative vertical movement in each of said side frames, means acting between each of the journal boxes and the adjoining side frame for resiliently supporting the side frames thereon, a hydraulic cylinder unit mounted in each side frame above each journal box and acting vertically therebetween, open piping hydraulically interconnecting said units for substantially instantaneonsly equalizing thereamong vertical forces applied to any thereof, and pressurized means connected to said piping for maintaining said piping and units lilled with liquid at a predetermined pressure.

l8. A railway truck comprising a bolster, side frames laterally connected by and rigid with said bolster, a plurality of journal boxes mounted for at least relative vertical movement in each of said side frames, means acting between each of the journal boxes and the adjoining side frame for resiliently supporting the side frames thereon, a single-acting hydraulic cylinder unit mounted in each side frame above each journal box and acting `vertically therebetween, open piping hydraulically interconnecting said units for substantially instantaneously equalizing thereamong vertical forces applied to any thereof, and pressurized means connected to said piping for maintaining said piping and units filled with liquid at a predetermined pressure.

9. A railway truck comprising a pair of side frames, a bolster extending laterally between and rigid with said side frames, a plurality of journal boxes for each side frame each mounted therein in a laterally and downwardly opening recess, mechanical springs at opposite sides of each recess and acting vertically between the journal box therein and the related side frame, a hydraulic cylinder unit mounted above each journal box in the related side frame and acting vertically therebetween, open piping hydraulically interconnecting said units for substantially instantaneously equalizing thereamong vertical forces applied to any thereof, and pressurized means connected to said piping for maintaining said units and piping filled with liquid at a predetermined pressure.

10. A railway truck comprising a pair of side frames, a bolster extending laterally between yand rigid with said side frames, a plurality of journal boxes for each side frame each mounted therein in a laterally and downwardly opening recess, mechanical springs -at opposite sides of each recess and acting vertically between the journal box therein and the related side frame, a hydraulic cylinder unit mounted above each journal box in the related side frame and acting vertically therebetween, open piping hydraulically interconnecting said units, and means associated with each unit for absorbing high frequency, low amplitude forces applied thereto.

11. A railway truck comprising a pair of side frames, a bolster extending laterally between and rigid with said side frames, a plurality of journal boxes for each side frame each mounted therein in a laterally and downwardly opening recess, mechanical springs at opposite sides of each recess and acting vertically between the journal box therein and the related side frame, a hydraulic cylinder unit mounted above each journal box in the related side frame and acting vertically therebetween, open piping hydraulically interconnecting said units, and means in each unit for absorbing high frequency, low amplitude forces applied thereto.

12. A railway truck comprising a pair of side frames, a bolster extending laterally between and rigid with said side frames, a plurality of journal boxes for each side frame each mounted therein in a laterally and downwardly opening recess, mechanical springs at opposite sides of each recess and acting vertically between the journal box therein and the related side frame, a hydraulic cylinder unit mounted above each journal box in the related side frame and acting vertically therebetween, open piping hydraulically interconnecting said units, and a resilient pad in each unit and impervious to the liquid therein for absorbing high frequency, low amplitude forces applied thereto.

13. A railway truck comprising a pair of side frames, a bolster extending laterally between and rigid with said side frames, a plurality of journal boxes for each side -frame each mounted therein in a laterally and downwardly opening recess, mechanical springs at opposite sides of each recess and acting vertically between the journal box therein and the related side frame, a single-acting hydraulic cylinder unit stationarily mounted in the related side frame above each journal box and acting vertically therebetween, open piping hydraulically interconnecting said units for substantially instantaneously equalizing thereamong vertical forces applied to any thereto, and pressurized means connected to said piping for maintaining said units and piping filled with liquid at a predetermined pressure.

14. A railway truck comprising a pair of laterally spaced side frames, a bolster extending laterally between and rigid with said side frames, each side frame having a plurality of downwardly and laterally opening recesses, a journal box mounted for relative vertical and lateral movement in each recess, mechanical springs at opposite sides of each recess and each acting vertically between the journal box therein and the related side frame, a hydraulic cylinder unit for and acting vertically between each journal box and the related side frame, each unit including a cylinder stationarily mounted in the related side frame above and substantially centered laterally in the adjoining journal box and a piston sliding in and projecting downwardly from the cylinder and bearing against a top wall of the journal box, a lubricious wearresistant plate inserted between each journal box and a piston of the related unit, a ring pipe mounted on said bolster about a center plate thereof and in open communication with said cylinders through lead pipes therebetween for substantially instantaneously equalizing thereamong vertical forces applied to any thereof, pressurized accumulator means mounted on said bolster and connected to said ring pipe for maintaining said pipes and cylinders filled with liquid at `a predetermined pressure, and regulator valve means interposed between said accumulator means and ring pipe for permitting free flow of liquid from said accumulator means to said ring pipe and regulating the ow thereof in the opposite direction.

15. A six wheel railway truck comprising a pair of laterally spaced unitary side frames, a bolster extending laterally between and rigid with said side frames, each of said side frames having three longitudinally spaced downwardly and laterally opening recesses therein, a journal box mounted for relative vertical lateral movement in each recess, mechanical springs at opposite sides of each recess and each acting vertically between the journal box therein and the related side frame, `a hydraulic cylinder unit for and acting vertically between each journal box and the related side frame, each unit including a cylinder stationarily mounted in the related side frame above and substantially centered laterally on the adjoining journal box and a piston sliding in and projecting downwardly from the cylinder and bearing against a top wall of the journal box, a lubricious wear-resistant plate inserted between each journal box and a piston of the related unit, a ring pipe mounted on said bolster about a center plate thereof and in open communication with said cylinders through lead pipes therebetween for substantially instantaneously equalizing thereamong vertical forces applied to any thereof, pressurized accumulator means mounted on said bolster and connected to said ring pipe for maintaining said pipes and cylinders filled with liquid at a predetermined pressure, and regulator valve means interposed between said accumulator means and ring pipe for permitting free flow of liquid from said accumulator means to said ring pipe and regulating the ow thereof in the opposite direction.

16. A railway truck comprising a pair of laterally spaced side frames, a bolster extending laterally between and rigid with said side frames, each side frame having a plurality of longitudinally spaced downwardly and laterally opening recesses, a journal box mounted for relative vertical lateral movement in each recess, mechanical springs at opposite sides of each recess and each acting vertically between the journal box therein and the related side frame, a hydraulic cylinder unit for and acting vertically between each journal box and the related side frame, each unit including a cylinder stationarily mounted in the related side frame above and substantially centered laterally on the `adjoining journal box and a piston sliding in and projecting downwardly from the cylinder and bearing against a top wall of the journal box, a resilient pad in the piston of each unit and exposed and inert to the liquid therein for absorbing high frequency, low amplitude forces, a lubricious wear-resistant plate inserted between each journal box and a piston of the related unit, a ring pipe mounted on said bolster about a center plate thereof and in open communication with said cylinders through lead pipes therebetween, pressurized accumulator means mounted on said bolster and connected to said ring pipe for maintaining said pipes and cylinders lled with liquid at a predetermined pressure, and regulator valve means interposed between said accumulator means and ring pipe for permitting free flow of liquid from said accumulatoimeans to said ring pipe and regulating the ow thereof in the opposite direction.

References Cited UNITED STATES PATENTS Bugatti 10S-208 X Wilson et al. 10S- 208.1 Furrer et al. 10S-224 X Bachman 105-197 Bachman 105-224.1 X Swander 10S-197 X Schumacher 10S-218 X Roberts l05*207 Brooks 213-36 Messier 105-171 Lucien 280-l24 Rusconi 280-104 ARTHUR L. LA POINT, Primary Examiner.

l5 HOWARD BELTRAN, Assistant Examiner.

U.S. C1. X.R. 

